Apparatus for trimming drawn sheet metal shells and the like



Apnl 9, 1963 D. H. DULEBOHN ETAL 3,084,576

APPARATUS FOR TRIMMING DRAWN SHEET METAL SHELLS AND THE LIKE Filed Sept. s, 1958 5 Sheets-Sheet 1 5/ WWW Apnl 9, 1963 D. H. DULEBOHN ETAL 3,084,576

APPARATUS FOR TRIMMING DRAWN SHEET METAL SHELLS AND THE LIKE Filed Sept. 8, 1958 5 Sheets-Sheet 2 //Vl f/V70/$ 94/00/74 01/1 EBOHN 5/ PaaawrM 60L0 D. H. DULEBOHN' ETAL 3,084,576 APPARATUS FOR TRIMMING DRAWN SHEET METAL April 9, 1963 SHELLS AND THE LIKE 5 Sheets-Sheet 3 Filed Sept. 8, 1958 April 9, 1963 Filed Sept. 8, 1958 D. H. DULEBOHN ETAL 3,084,576 APPARATUS FOR TRIMMING DRAWN SHEET METAL SHELLS AND THE LIKE 5 Sheets-Sheet 4 I 1 vitg uwhmxwru ATTOR/Vi-"XS April 9, 1963 D. H. DULEBOHN ETAL 3,084,576

APPARATUS FOR TRIMMING DRAWN SHEET METAL SHELLS AND THE LIKE 5 Sheets-Sheet 5 Filed Sept. 8, 1958 United States Patent APPARATUS FGR TRIMMENG DRAWN SHEET METAL SHELLS AND THE LEKE a David H. Dnlebohn and Robert M. Gold, Minneapolis,

Minn, assignors to Dayton Rogers Manufacturing (10., Minneapolis, Minn, a corporation of Minnesota Filed Sept. 3, 1958, Ser. No. 759,619

4 (Ilaims. (Cl. 82-46) This invention relates to apparatus for trimming the peripheral edges of drawn sheet metal shells and the like.

It has been common practice in the past in apparatus for trimming the peripheral edges of drawn sheet metal shells and the like to produce the cut 'by means of simple shearing action between the cooperating edges. Several disadvantages and drawbacks have been encountered in connection with these prior art methods. Firs-t, it has been found that unnecessarily large quantity of power has been consumed in this cutting operation. Secondly, it has been experienced that the cutters will frequently skip along certain portions of the edge so that the shell is not truly trimmed in a single operation and subsequent operations are necessary to complete the trimming. This frequently results in defective shells which may even have to be rejected and scrapped. Thirdly, a disadvantage of the prior art apparatus employed to trim the peripheral edges of shells is that such apparatus frequently caused the shell to be deformed, particularly at the corner sections of certain types of shells.

With these comments in mind, it is to the elimination of these and other disadvantages that the present invention is directed, along with the inclusion therein of other novel and desirable features.

An object of our invention is to provide a new and improved machine of relatively simple and inexpensive construction and operation for trimming the peripheral edges of drawn sheet metal shells and the like.

Another object of our invention is the provision of a novel machine for trimming the peripheral edges of drawn sheet metal shells and the like by means of a slicing action between cooperative cutting edges such that the point of cutting moves along one of the edges at a speed which is different than the movement of the point of cutting along the other cutting edge with the result that a material savings of power necessary to trim the peripheral edge is obtained.

A still further object of our invention is to provide an improved and novel machine for trimming the peripheral edges of drawn sheet metal shells and the like, which machine is constructed to facilitate rapid setup for the handling and trimming of shells of different shapes and sizes so as to materially reduce the cost of short run operations.

A further object of our invention is to provide a new and novel method of developing the cutting edge of a knife which is to be moved linearly along in cooperative cutting relation with a cutting edge on a rotary mandrel wherein the knife edge has such a configuration as to permit movement of the knife at such -a speed that the knife will move faster than the mandrel at the point of cutting.

A still further object of our invention is the provision of an improved machine for trimming the peripheral edges of sheet metal shells and the like wherein the edge of the shell is trimmed by cooperative cutting action between an edge on the shell-mounting mandrel and a cooperative linearly moving knife and wherein the linearly moving knife effectively prevents any relative movement between the rotary mandrel and the shell mounted thereon.

A still further object of our invention is the provision of a novel machine for trimming peripheral edges of drawn sheet material shells and the like by means of a slicing action between cooperative cutting edges such that the point of cutting moves along one of the edges at a ice speed which is different than the movement of the point of. cut-ting along the other cutting edge with the result that the speed of trimming is not limited by either the shape or configuration of the shell being trimmed or by the trimming action, but on the other hand, the speed of trimming is only limited by the practical modes of producing such movement in the design of the machine.

These and other objects and advantages of our invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same parts throughout the several views and in which:

FIG. 1 is a perspective view of the invention;

FIG. 2 is a detail section view taken on a substantially vertical plane substantially at 22 in FIG. 1- but with the mandrel removed;

FIG. 3 is a detail elevation view of a portion of the mechanism showing the trimming knife and mandrel in a shifted position as compared to FIG. 1 and at a position wherein the cutting of the shell has been completed;

FIG. 4 is a detail elevation view taken on a plane as indicated substantially at 4-4 in 'FIG. 3;

FIG. 5 is a detail section view taken on a vertical plane which is oriented substantially at the line 5-5 in FIG. 1;

FIG. 6 is a schematic diagram of the hydraulic circuit of the present invention;

FIG. 7 is a schematic diagram of the electrical circuitry of the invention with controls shown for the automatic mechanism shown in FIGS. 11 and 12;

FIG. 8 is a somewhat diagrammatic detail elevation view of a modified form of trimming knife which may be employed with the mandrel for trimming the peripheral edge of the shell;

FIG. 9 is a perspective view of the disassembled trimming knife, mandrel, shell delivery member of the auto loading mechanism and an. untrimmed shell and a trimmed shell, all of which are representative of another setup of the machine for use with these shells of a different shape;

FIG. 10' is a perspective view of the disassembled trimming knife, mandrel, shell delivery member of the auto loading mechanism and an untrimm'ed shell and a trimmed shell, all of which are representative of another setup of the machine for use with shells of a different shape;

FIG. 11 is a front elevation view of the automatic loading mechanism applicable to the shell trimming machine which is shown in part in dotted lines behind the automatic loader to show the orientation of the loader when applied to the machine; and

FIG. 12 is a detailed vertical section view of the auto loader mechanism shown applied to the trimming machine which is shown in part in dotted lines, the section being taken along a vertical line substantially at 12-12 as indicated in FIG. 11 and the guide bars of the auto loading mechanism have been removed in FIG. 12 for clarity of detail;

FIG. 13 is a plan view of an accessory for use in developing the contour of the trimming knife edge; and

FIG. 14 is a transverse section taken on a plane as indicated at 14- 14 in FIG. 13.

One form of the present invention is shown in the figures and is described herein. The shell trimming machine includes a frame structure which is indicated in general by numeral it} which defines an enclosed housing, part of the interior of which is employed as a reservoir for the oil of the hydraulic system and part of which encloses the automatic controls. The frame structure 10 carries a longitudinally moving slide, which is indicated in general by numeral 11 on the upper portion thereof and ways 12 are provided on the front and rear of the frame structure for receiving the gibs 13 of the slide 11.

The slide is reciprocated by means of a hydraulic cylinder 14 which is carried on the slide and has the piston rod 15 thereof anchored by means of a bracket 16 to the frame structure 10 of the machine. It will therefore be seen that by operation of the hydraulic cylinder the slide 11 will be reciprocated back and forth along the ways 12. The slide 11 has rigidly afiixed thereto and at the front side, an elongate trimming knife-seating structure 17 which includes a plate 18 behind a downwardly facing shoulder surface 19 against which the trimming knife 20 is seated and is removably secured as by clamps 21 which bear against the outer surface of the knife 20 and which are secured as by screws to the structure 17.

The slide 11 also carries a longitudinally extending rack 22 for purposes hereinafter more fully explained.

The frame structure 10 also carries on suitable bearings 23 which are designed to support against end thrust, a rotary mandrel-mounting carriage which is indicated in general by numeral 24. The integral body 25 of the rotary carriage 24 has a pinion 26 on the periphery thereof and meshed with the rack 22 of slide 11. The carriage 24 is provided with an end plate 27 secured to the carriage body 25 as by screws 28 and sealed against the cylindrical wall 29 of the frame structure in which the carriage 24 is mounted by means of an oil-sealing ring 30. The carriage body 25 and end plate 27 define a cylindrical interior chamber 31 for purposes hereinafter more fully set forth.

The carriage 24 also has a generally circular mandrelmounting bolster 32 which is affixed in coaxial relation on the end plate 27 by means of a plurality of screws 33. The bolster 32 has, at the outer side thereof, a substantially diametrically extending keyway or guiding groove 34, and also has a plurality of tapped apertures 35 extending therethrough. In FIG. 2 certain of the tapped apertures 35 are shown blocked by means of threaded plugs 35 therein.

As best seen in FIGS. 1, 3 and 4, a shell-mounting mandrel 37 is mounted on the bolster 32 through the use of an adapter 38 which fits into the guideway 34 and a plurality of screws 39 for securing the mandrel to the adapter and for securing the adapter to the bolster in a plurality of the tapped apertures 35. The mandrel 37 is shaped to conform to the interior configuration of the shell which is to be trimmed. In the example shown in FIGS. 1, 3 and 4 the mandrel is oblong in shape so as to receive an oblong shell thereover. The inner portion 37a of mandrel 37 is of reduced size so as to define a cutting edge 40 around the entire periphery of the mandrel and spaced from the outer end of the mandrel so as to underlie the shell when applied. It will be seen in FIGS. 3 and 4 that the slicing edge 41 is disposed in alignment with the cutting edge 40 of mandrel 37 and in overlapping cooperative cutting relation therewith. At this point it is well to note that because of the non-circular configuration of the mandrel 37 in this particular example, the slicing edge 41 of knife 20 is developed along a curved line so that the edges 40 and 41 remain in overlapped cooperative cutting relation with each other as the mandrel is revolved and as the knife 20 moves with the slide 11. The manner in .which the knife edge 41 is developed is hereinafter more fully set forth.

. An important phase of the present invention should be emphasized at this point. It should be specifically noted that the pitch diameter of the pinion 26 is in excess of twice the maximum radial distance from the center of rotation to the mandrel periphery, or in other words, the mandrel periphery is, at every point disposed inwardly of the circumference of the pinion 26. As a result, the linear speed of the knife edge 41 at the point of convergence or the point of cutting on the mandrel when the knife is moving in the direction of arrow A, is in excess of the linear speed of a corresponding point on the mandrel periphery. Because the knife edge 41 travels faster at the point of cutting than does the mandrel edge 40 the shell periphery is cut with a slicing action as contrastedl with more conventional shearing action. The slicing ac-' tion in the cutting of the shell periphery has several ef-- fects, the most important of which are that the overall power necessary to produce the cutting of the shell periphery is materially reduced as contrasted with other previously known methods of trimming shells; in addition, the knife edge continuously urges the shell tightly against the mandrel at the point of cutting so as to prevent any possible relative movement between the shell and mandrel, and this becomes particularly important in the case of a truly circular shell on a circular mandrel wherein the faster linear speed of the knife actually urges the shell in the direction that the mandrel is turning so as to prevent any back-slipping of the shell on the mandrel as the edge is being trimmed; and a further important effect of the slicing action is to provide a substantially constant cutting force exerted on the stock by the trimming knife, even at sharp corners of the shell such as in the case where the shell is rectangular or square; furthermore, the shells may be trimmed extremely quickly because there is no skip cutting whatsoever. It should also be noted that the slicing action is obtained in trimming non-circular shells, peripheral portions of which are disposed outside the circumference of pinion 26. Certain peripheral portions of such shells may be disposed outside the circumference of pinion 26 and other peripheral portions of such shells may be disposed inwardly of the circumference of pinion 26, but regardless of whether the portions of the shell} peripheries are outside the pinion circumference or inwardly from the pinion circumference, there is still an relative motion producing slicing action between the knife edge andthe mandrel and substantially all of the ad vantages hereinbefore are obtained. Ordinarily, the shell is mounted on the mandrel symmetrically about the rotation axis. The length of such shells may exceed the pitch diameter of the pinion 26 and the slicing action is still obtained.

Means are provided for holding the shell on the mandrel 37 during trimming of the edge of the shell. In the form shown, such means include a hold-down device or member 42 which is swivelly connected to the piston rod '43 of a hydraulic cylinder 44 which is carried on a bracket 45 at the front side of the frame structure 10. The holddown member 42 is movable when the cylinder 44 is operated toward and away from the mandrel 37 so as to engage the shell on the mandrel and hold the shell in such a position that the inner end portion of the shell overlies the cutting edge 40 of the mandrel. As the mandrel is revolved the hold-down device 42 rotates with the mandrel and shell.

Means are also provided for ejecting the shell from the mandrel when the edge of the shell has been trimmed. In the form shown, such means includes an opening 46 through the bolster 32 and aligned openings 47 and 48 through the adapter 38 and mandrel 37 respectively. In certain instances, one or more of the tapped apertures 35 in bolster 32 may be employed. The ejecting means also includes a pressure-exerting media movable through an opening in the bolster and through the aligned openings in the adapter and mandrel for bearing against the inner side of the shell on the mandrel and moving the shell off the mandrel. The pressure-exerting media may take different physical forms and in one form the pressure-exerting media may comprise air moving under pressure through the openings '46, 47 and 48 for effectively blowing the shell off the mandrel. The pressure-exerting media may also comprise one or more ejector pins 49 which are slidable through apertures 35 in the bolster 32. The pins 49 will be aligned with apertures such as 47 and 48 in the adapter and mandrel for permitting the pins to project through the mandrel and knock the shell oi the mandrel. The position of the pins shown in FIG. 2 is cited as exemplary and it should be understood that pin 49 may be positioned at substantially any desired location depending upon the size and configuration of the mandrel and the corresponding shell to be ejected therefrom. In some cases the ejecting may be exclusively accomplished by the pin 49 and the air ejection is not employed; and in other cases, it may be desirable to use only the air ejection of shells and in other cases it may be desired to use a combination of the air and pin ejection such as in the case of shells of lightweight material wherein it is desired to start the ejection by means of a pin and then blow the shell off the mandrel.

feans are provided for operating the pressure-exerting media, and in the form shown, such means include an air-operated cylinder 56 having a piston rod 51 which is connected through a bearing '52 to a pin-mounting plate 53 in the opening 31 of the carriage body 25. The mounting plate 53 is rotatable with the carriage 24 and is driven in rotation by the carriage through a plurality of pins 54 Which are slidable in openings in the carriage body 25 and which are affixed in the clamping rim 55 which secures the bearing 52 with respect to mounting plate 53 and is connected to the plate 53 by means of screws 56. The cylinder Si) is afiixed to a portion lltla of the frame structure 13 and is non-rotatable. Air is supplied to the double-acting cylinder 50 through ports 57 and 58 and the speed of operation of cylinder St is controlled by a speed control apparatus 59 which is connected in the line for the port 53. The control apparatus may vary the rate of flow of air by operating the manual control 60.

The piston rod 51 has an opening 61 extending endwise therethrough and the inner end of the opening 61 in piston rod 51 is connected by means of a telescopic pipe within the cylinder 50 to an air supply conduit 62 which may be suitably controlled as by valve and is connected to a source of air under pressure. The pin-mounting plate 53 also has a central opening 63 therein in alignment with the opening 61 in the rod 51. Air supplied through the conduit 62 and through the openings 61 and 63 is em ployed for exerting pressure against the shells for ejecting the same.

Means are provided for cutting .or splitting the ring of scrap trimmed from each of the shells into two pieces to permit the scrap to quickly fall from the inner end portion of the mandrel. In the form shown, the inner end portion 37a of the mandrel is provided on opposite sides thereof with a pair of anvils 64 defining shearing edges 65' which cooperate with the shearing edges 66 of scrap knives 67. The scrap knives 67 are affixed as by screws 68 to slides 69 which are guided in ways 70 for reciprocating movement in a predetermined position. The ways 70 are defined by stationary blocks 71 aflixed as by screws 71a to the frame structure of the machine, and also by a removable or adjustable block 72 which is afiixed as by screws 72:: to the stationary block 71. The piston rods 73 of hydraulic rams 74 are connected to the slides 69 for moving the scrap knives 67 toward and away from the mandrel 37. The hydraulic rams 74 are fixed to the frame structure, but are mounted for longitudinal adjustment. The end mounting members 75 of the hydraulic ram 74 are slidable along the frame structure and are normally, but releasably clamped in stationary position by a clamp bar 7 6 which is secured to the frame structure as by screws 77. Threaded rods 78 are connected to the outer end members 75 of the ram 74 and are threaded to suitable bushings 7i affixed to the frame structure. Crank handles 89 are provided on the outer ends of the threaded rod 78 for turning the same and adjusting the longitudinal position of the hydraulic rams 74 whereby to adjust the inner limits of movement of the scrap knives 67 so that they will overlap the anvil edges 65 in cooperative cutting relation.

It should be noted that the scrap knives 67 are shaped at their inner sides 67a to fit into and be guided by the guideway 34 in the bolster 32 so that the scrap knives are accurately positioned when they move into cutting relation with the anvil edges 65. It should be understood that the limit of movement of slide 11 is so positioned as to cause orientation of the bolster 32 so that the guideway 34 is precisely aligned with the scrap knives when the trimming around the periphery of the shell by the knives has been completed.

it should be pointed out that the movements of the slide ll, the scrap knives 67 and the hold-down device 42 operate various limit switches and hydraulic valves which, for the most part, are not shown physically in the drawings but are schematically shown in FIGS. 6 and 7 and will hereinafter be more fully described.

in FIGS. 11 and 12 the automatic loading mechanism is shown and is indicated in general by numeral 81. The automatic loading mechanism is constructed to deliver untrimmed shells to the mandrel, one at a time, so that when the hold-down cylinder 44- is operated, the holddown device 42 will move the shell into seated condition on the mandrel. in this regard, it will be noted that the loading position of the mandrel 37 must be identical for each cycle of operation and therefore the slide 11 must have a predetermined limit of movement when returned to start position. The automatic loading apparatus 81 includes a delivery member or shell carrier 82 which is movable transversely of the rotation axis of the mandrel 37 and is movable into substantial align ment with the mandrel for delivering a shell 83 to the mandrel. The carrier 82 has a recess 84 therein which is contoured to fit the external periphery of the particular shell being handled. The carrier 82 is connected to the piston rod 85 of an air cylinder 86 which is affixed to the loader frame 87. The loader frame is adjustable inwardly and outwardly with respect to the supporting structure lit of the machine and with respect to the mandrel 37 by means of a threaded rod 88 which is journalled in a bracket 39 affixed to the frame structure 10. Rod 88 is threaded to the loader frame 87 as at 83a for moving the loader frame toward and away from the mandrel. An elongate and inclined plate 90 disposed in a vertical plane and affixed to the loader frame 87 has a plurality of elongate and parallel guide rods hi mounted thereon for adjustment in multiple directions toward and away from each other for defining a guideway 9942 through which the shells 83 are supplied in predetermined orientation to the carrier 82. Rods 91 each have a plurality of mounting arms 91a thereon which are slidable through brackets 92, but may be affixed with respect to the brackets as by set screws. The brackets 92 are swingably mounted on shafts 93 and are securable in predetermined position thereon as by set screws. The shafts 93 are secured to the mounting plate 99 as by fixtures 94. It will thereby be seen that by swinging the brackets 92 with respect to shafts 93 and by slidably adjusting the mounting arms 91:: with respect to the brackets 92, the guideway 99a may be shaped in thickness and width to accommodate shells of substantially any size and configuration for guiding the shells along the plate 91 downwardly to the carrier 82. A shoe 82a is atfixed to the carrier 82 for restraining downward movement of shells in the guideway 9% while the carrier 82 is projected by operation of cylinder 26. A photoelectric cell 95 is mounted on the loader frame $7 at the lower end of the guideway 96a and opposite a source of light 96 which may be carried on the holddown cylinder mounting bracket 45 substantially as shown in dotted lines in FIG. 1 to detect the presence of a shell in the carrier 82.

In FIG. 9 is shown an untrimmed square shell 97 as contrasted to the oblong shell which fits over the mandrel 37 shown in FIGS. 1, 3 and 4. The untrimrned shell 9'7 will be trimmed as shown at 97a after the machine has been set up with the trimming knives 2% applied to the slide 11 and after the mandrel 37 is applied in place of the mandrel 37' to the bolster. It should be noted that the mandrel 37 has an anvil edge 65' at the front side thereof. The carrier 82' is applicable to the 7 automatic loader to feed the square untrimmed shells to the mandrel.

In FIG. 10 the circular mandrel 37 will receive an untrimmed circular shell 98 thereover and will cooperate with the straight edged knife in trimming the shell into the condition shown at 98a. The delivery member or carrier 82" is applicable to the automatic loader for supplying the untrimmed shells to the mandrel.

The hydraulic circuit shown in FIG. 6- shows, diagrammatically, the cylinder 14 for operating slide 11, the scrap knife cylinders 74, the hold-down cylinder 44 and valve apparatus for operating these cylinders. The reservoir of oil contained in a portion of the housing defined by the supporting structure of the machine 10 is moved into the main hydraulic conduits 93 by means of a pump 100 driven by a motor 101. The supply of oil to the hold-down cylinder 44 is controlled by a double-acting valve 102 having hydraulic control devices 102a, the operation of which is controlled by a valve 103 which is controlled by an electric solenoid 104. Valve 103 is supplied with hydraulic fluid under pressure through a conduit 103a which is connected to the main hydraulic conduit 99. In the hydraulic line 44a connected to cause pressure therein to extend the piston rod, is provided ta pressure-reducing valve 105 of conventional design which closes after sensing a predetermined back pressure from within the cylinder 44 so as to limit the pressure in the cylinder and thereby limit the force applied by the holding device 42 against the shell on the mandrel. The cylinder return conduit 44b is connected directly to valve 102.

The main oil line 99 is connected to cylinder 14 through a valve 106 which has hydraulically operated controls 10611 which are controlled by oil under pressure from conduits 1117 and 108 which are connected to a reversing valve 109 which is operated by hydraulic controls 109a. The controls 109a are operated by a reversing valve 110 which is operated by means of an electric solenoid 111. The valve 110 is supplied with fluid pressure through a conduit 110a which is connected to the main pressure line 99. The cylinder return conduit 14a of cylinder 14 has a sequence valve 112 therein to prevent operation of cylinder 14 on the return stroke until a predetermined hydraulic pressure exists in the main conduit 99, which pressure cannot be attained until all of the other cylinders and particularly the scrap knife cylinders 74 are stationary.

The scrap knife cylinders 74 are operated by a reverse valve 113 having hydraulic controls 113a and 11'3b. The hydraulic control 113a is connected to conduit 107 and is controlled by valve 109 and solenoid 111. The control 113b is connected through a mechanically operated hydraulic valve 114 which is operated by the knife slide 11 when the slide has reached its limit of movement (left hand as viewed in FIG. 1) and when the cylinder 14- is fully extended. It should be noted that the valve 114 is supplied from conduit 11411 which is connected to the conduit 44a and is controlled by valve 1t ?r so that the scrap knife cylinders can only operate when the holddown cylinder is extended so that the shell is positively held on the mandrel.

Lubrication for the machine is provided at conduits 115 through a filter 115a and a supply conduit 11512 which is connected to the conduit 110a.

With regard to the electrical circuitry shown in FIG. 7 for operating the shell trimming machine, a source of single phase three wire power is provided at 116 and may be controlled by a master switch 117 and fuses 118. Each of the conductors to motor 101 has normally open relay contacts M1, M2 and M3 respectively which are operated by relay M. The power to the electrical controls is provided through a transformer T and the secondary of the transformer may be connected by a fuse 118a to a pair of electrical buses 119 and 120. Bus 120 is connected through a normally closed emergency return manually operated switch 121 to another bus 12-2 which is normally energized. The relay M is connected directly to bus 119 and is connectible to bus through a normally open start switch 123, a normally closed stop switch .124 and normally closed overload contacts 125 which are controlled by suitable overload mechanism. Normally open contacts M4 of relay M shunt the start switch 123 and hold the relay M energized after the start switch 123 has been momentarily closed. A number of limit switches are provided on the machine for use in cycling the operation of the various cylinders. A limit switch LS1 is mounted on the hold-down cylinder bracket 45 and has a normally open contact which is operated, or closed, when the hold-down cylinder is fully extended and when the shell has been seated on the mandrel. Another limit switch LS-Z, having a normally closed contact LS-Za and a normally open contact LS-Qb, is mounted on the frame structure 10 of the machine and is held in its normal position by the retracted scrap knives and the contacts are caused to shift when the scrap knives advance inwardly toward the mandrel. Another limit switch LS-3 has a pair of normally open contacts LS3a and LS-3b, and is mounted on the automatic feeder frame 8 7 and the contacts thereof are held in their nor mally open position by the retracted feeder and the contacts are closed as the air cylinder 86 is extended and the shell carrier 82 is moved inwardly toward the mandrel. Another limit switch LS-4 having a normally open contact LS-4a and a normally closed contact LS-4b, is mounted on the frame structure 10 of the machine and the contacts are held in their normal positions by the knife slide in its normal or start position and the contacts are shifted as the knife slide advances.

The electrical circuit also includes a number of relays respectively designated CR1, CR2, CR3 and a time delay relay designated TDR and a detecting mechanism including a relay D operating in response to light striking :the photocell 95. Relay CR1 has four contacts, CR1a, CR1-d, all of which are normally open except CR1-d. Relay CR2 has four contacts CR2-a, CRZ-d, all of which are normally open except contact CR2-a which is normally closed. Relay CR3 has a pair of contacts CR3a and CRS-b, both of which are normally open. Relay D has a pair of normally open contacts D-1 and D-Z. Time delay relay TDR has three contacts TDR-1, TDR-2 and TDR-3; the time delay relay operates immediately upon being energized to close the contacts TDR-2 and TDR-3 and after a short time delay the contacts thereof will reopen.

The electric circuit also has a pair of multiple contacts two-position selector switches 126 and 127 having contacts 126a 126d, and 127a 127d. The selector switches 126 and 127 are provided to facilitate operation of the machine by manual loading of the shells onto the mandrel, in which case manual starting of each cycle of the machine is necessary, and also permits automatic loading and automatic cycling of the machine if the mechanisms of FIGS. 11 and 12 is employed.

A pair of multiple contact push button switches 128 and 129 are provided for starting the cycle of operation, and these switches have contacts 128a, 128b, 12-80, 12911, 12% and 1290.

The relay CR1 is connected directly to bus 119 and is connectible to bus 122 through contacts CR3-a, CR2a, and either contact CR1a or limit switch LS-4b, contacts 126a, 128a and 129a. The contacts 126a and 128a and 1290 are shunted by contacts D1, 126 h and CRS-c; and contacts D1, 126b and CR3-c may be shunted by contact 127a. Detector relay D is connected directly to bus 119 and is connectible to bus 122 through contacts 12 6b and contact DRG-c or through the other shunt circuits mentioned when the proper contacts are closed.

The solenoid 104, for operating the hydraulic valve controlling the hold-down cylinder 44, is connected directly to bus 119 and is connectible to bus 122 through limit switch LS2a, contacts CRl-b, 127b, 12-8b and 12%. Relay DR2 is connected directly to bus 119 and is connectible to bus 122 through limit switch LS1 and contact CR2-b; and relay CR2 is also connectible to bus 122 through limit switch LS=3a; and relay CR2 is also connectible to bus 122 through contacts CR1-b, 127b, 1281? and 12%. Relay CR3 is connected directly to bus 119 and is connectible to bus 122 through either contact CR3b or contact 1260 and 1270. Time delay relay TDR is connected directly to bus 1H and is connectible to bus 122 through contact TDR-1 and either contact TDR-2 or limit switch LS.2b and contact CR2-c.

A voltage reducing transformer T1 has its primary connected directly to the buses 119 and 122. Electric solenoids 130 and 131 are connected in the secondary circuit of transformer T1 and are operatively connected with air valve apparatus 132 for controlling the operation of the air cylinder 86 of the auto loading mechanism 81. When solenoid 130 is operated, the air is supplied to cylinder 86 to project the piston rod and move the carrier 82 toward the mandrel and when solenoid 131 is energized, the air valve apparatus is operated to retract cylinder 86 and cause return of the carrier 82 into alignment with the shell guideway 90a. The solenoid 13% is connected directly to one side of the transformer secondary and is connectible to the other side of the transformer secondary through contacts CRl-c and either contact D-2 and 126a, or 127d, 128c and 12%. The solenoid 131 is connected directly to one side of the transformer secondary which is connectible to the other side of the secondary through contacts LS-3b and CRl-d.

The solenoid 111 which controls the operation of the valves for applying hydraulic pressure into the cylinder 14 for operating the slide, is connected directly to bus 119 and is connectible to bus 122 through contact CR2d. A solenoid 133 is provided for operating the air valve apparatus 134 for controlling the air supplied to the ejector cylinder 80 and for controlling the air supply to the tube 62 for air blasting the shell off the mandrel. When the solenoid 133 is energized, the air supply for operating cylinder 50 and for air blasting the shell off the mandrel and when the solenoid 133 is deenergized, the cylinder 59 is retracted and the air supply through conduit 62 is stopped. Solenoid 133 is connected directly to bus 119 and is connectible to bus 122 through contact TDR3.

Operation The operation of the shell-trimming machine is first described in connection with the mechanical movements without making detailed reference to all the operations of the hydraulic circuit and of the electrical circuit. It is assumed that a properly shaped mandrel has been applied to the bolster 32 to receive the correspondingly shaped shells, and a properly developed knife 2% is clamped to the carriage 11.

With the carriage 11 in start position so that the edge of the knife 21) is out of engagement with the mandrel 37, a shell is applied onto the mandrel so that the untrimmed edge portion overlies the cutting edge 41 of the mandrel. The hold-down cylinder 44 is then operated to move the hold-down member 42 into engagement with the shell on the mandrel so as to positively seat the shell and thereafter hold the shell on the mandrel. The slide 11 is then pulled by means of the cylinder 14 to the left in FIG. 1, causing the slicing edge of the knife m engage the periphery of the shell and to slice therethrough and the knife then moves into overlapped cooperative cutting relation with the mandrel cutting edge 40. As the carriage 11 is moved linearly, the rack and pinion 22 and 26 respectively cause rotation of the rotary carriage 24' which causes corresponding rotation of the mandrel 37.

As hereinbefore pointed out and emphasized, the knife edge 41 at the point of cutting of the shell moves in a substantially similar direction as does the corresponding point on the periphery of the mandrel edge 46 but the speed of the knife edge 41 exceeds the speed of the cutting edge 41) and a slicing action of the mandrel periphery is thereby obtained. The rotation of the mandrel 37 continuously moves new portions of the shell periphery into position to be out between the edges 40 and '41 and ultimately, by the time the mandrel 57 has made a complete revolution, the entire length of knife edge 41, which is longer than the circumference of the mandrel cutting edge 4%, will have passed along the mandrel cutting edge and the entire shell periphery will have been trimmed. Actually, as will be seen by comparing FIGURES l and 3, the mandrel revolves slightly more than a complete revolution, but it should be understood that when the mandrel is in the position shown in FIG. 1, the knife edge 41 is not in engagement with the mandrel.

At the end of the cutting stroke of the knife 20, the slide 11 and rack 22 will have rotated the carriage 24 and bolster 32 into the position shown in FIG. 3 wherein the guideway 34 in bolster 32 is disposed in precise alignment with the inner keying portions 67a of the scrap knives 67. While the carriage 11 remains in its fully extended position, the scrap knives 67' are moved inwardly by operation of the cylinders 74 and the inner keying portions 67a will slide into the guideway 34 and the cutting edges 66 of the scrap knives will move into proximity with the anvil edges 65. The ring of scrap which is trimmed from the shell will be surrounding the inner portion 37a of the mandrel and when the cutting edges 66 of the scrap knives move into shearing relation with the anvil edges 64, the ring of scrap surrounding the inner portion of the mandrel is split at opposite sides thereof into two pieces so that the scrap will fall freely from the mandrel. If the scrap does not fall immediately it will do so momentarily when the bolster and mandrel is revolved to its start position. After the scrap knives have split the ring of scrap, the hold-down cylinder 44 is retracted so as to move the hold-down member 42 out of engagement with the shell. After this has occurred, air under pressure is supplied through the conduit 62 and through the opening 61 in the piston rod 51 so as to move air through the openings 46, 47 and 48 for impelling the shell off the mandrel. It should be understood that at this time, the ejecting cylinder 50 is operated so as to move the ejector pins 49 outwardly (if any are used in the particular setup) so as to knock the shell off the mandrel. Of course the ejector cylinder is retracted so as to retract the ejector pins 49 and then the scrap knives are retracted by operation of the hydraulic cylinder 74, and when the scrap knives have been retracted, the slide 11 and knife 20 is retracted to start position and simultaneously the rotary carriage 24 and mandrel 37 is also revolved back to start position. During this revolving of the mandrel, any pieces of scrap that may be left on the mandrel will drop otf.

If the automatic feeder or loading mechanism 8 1 is being used, the return of the slide 11 to start position will trigger operation of the air cylinder 86 so as to move the carrier 82 into alignment with the mandrel, whereupon when the hold-down member is again actuated, the shell carried by the carrier 32 will be driven onto the mandrel 37. As the carrier 82 moves toward the mandrel, the shoe 82a will restrain downward movement of any other shells in the guideway 9M and when the carrier 82 has been returned to its normal position, another shell from the guideway 96a will move downwardly into the carrier.

More specifically now in regard to the operation of the electric and hydraulic circuit, it will first be assumed that the automatic loading mechanism switch is in off position and the selector switch 126 is positioned for single stroke operation. The motor start button 123 is pushed to energize relay M which connects the motor for driving the hydraulic pump 1G0. Relays CR1 and CR3 will have previously been energized and each of these relays is held in energized condition through reans gave 11 spective contacts thereof. When it is desired to start the operating cycle of the trimming machine, a shell applied to the mandrel as previously described and then the dual cycle-starting push buttons 128 and 129 are momentarily depressed and then released. Closing of contacts 128b and 1291) causes energization of solenoid viously mentioned, the pressure in hold-down cylinder 44 is maintained at a maximum which is substantially less than the pressure in the line 99. When the shell has been seated the limit switch LS1 is operated so as to cause energization of relay CR2 through contacts CR1-b, 127b and contacts 128!) and 12% which are still manually held in closed condition. Relay CR2 is maintained in energized condition by contact CR2-b after the cycle start switches 128 and 129 are released; and contacts CRZ-b also hold solenoid 104 in energized condition. Contact CR2a opens to cause relay CR1 to drop out and return the contacts thereof to normal. Contact CR2-c closes to prepare for subsequent energization of the time delay relay TDR. Contact CR2-d closes to energize solenoid 111 which operates hydraulic valve 110 for causing operation of valve 109, which, in turn operates valve 106 for directing hydraulic fluid into the operate end of cylinder 14 for moving the slide 11. As previously mentioned movement of the slide 11 causes commencement of trimming of the shell and the slide 11 will stop at the end of its stroke when the cylinder 14 is fully extended.

When the cylinder 14 is fully extended, the slide operates limit switch LS-4, causing contact LS-4a to close to operate the counter 135.

Advancement of slide '11 into its limit of movement also causes mechanical operation of the hydraulic valve 114 which causes operation of valve 113 to apply hydraulic fluid under pressure to the operate ends of scrap knife cylinders '74. The scrap knives advance and split the ring of scrap trimmed from the shell and when the scrap knives 67 are fully extended, the limit switch LS-2 is operated to open contact LS2a which deenergizes solenoid 104 for allowing valve 103 to return to normal position which causes operation of valve 102 so as to connect the conduit 44b to the high pressure fluid line 99 and connect the conduit 44a to the reservoir. The hold-down cylinder retracts the hold-down member 42. Contact LS2b closes to energize the time delay relay TDR which, immediately operates the contacts TDR-2 and TDR-3 which respectively hold the time delay relay energized and operate the air valve-operating solenoid 133 for causing ejection of the shell from the mandrel. As the hold-down device 42 moves away from the mandrel, the limit switch LS-1 returns to its normal position and relay CR2 is thereby deenergized to allow the contacts thereof to return to normal positions. Contact CR2a recloses to energize relay CR1 again. Contact CR2-d reopens to deenergize solenoid 111 which allows hydraulic valve 110 to return to normal position for operating valve 109. Operation of valve 109 has a dual effect when pressure is applied into conduit 107. Valve 113 is operated as well as valve 106 so as to connect the retract sides of the scrap cylinders 74 and the slide cylinder 14 to the hydraulic pressure line 99. As a result, the pressure in the line 99 Will immediately drop to some extent and the sequence valve 112 will prevent retracting of the cylinder 14 and movement of the slide 11 until the scrap cylinders 74 have fully retracted the scrap knives, at which time the pressure in the line 99 is allowed to build up to the point where the sequence valve 112 will permit application of hydraulic fluids under pressure to the retract end of cylinder 14 for returning the slide 11 to normal position. When the scrap knives are retracted, the limit switch LS-Z is operated so as to reclose the contact LS-2a to prepare for subsequent operation of solenoid 104 in the next cycle of operation, and contact LS2-b is closed for preparing time delay relay TDR for operation. When the slide 11 is returned to its start position, the limit switch LS-4 is operated to reopen contact LS4a and to close contact LS-4b.

The trimming machine and the hydraulic and electrical circuits are now in condition to permit starting of another operating cycle at which time another shell is applied to the mandrel and the cycle starting switches 128 and 129 are operated again.

When the automatic loading mechanism 81 is applied to the machine and the switch 126 is turned to provide automatic operation of the electrical circuitry, it will be seen that the relay CR1 is normally deenergized and the relay CR3 is normally energized after it has once been energized. The detector mechanism including the photoelectric cell detects the presence of a shell in the carrier 82 and causes operation of the detector relay D which closes contact D2 thereof for operating the solenoid 130 which operates the air valve for applying air to the cylinder 86 of the automatic feeding mechanism which causes the carrier 82 to advance and position a shell in front of the mandrel. When the carrier 82 is fully extended, the limit switch LS-3 operates, causing contact LS3a to close and thereby energize solenoid 104 for operating the hold-down cylinder which produces movement inwardly toward the mandrel of the hold-down device 42 and thereby moves the shell 05 the carrier 82 and onto the mandrel. Operation of the machine proceeds as previously described, but in addition the contact LS-3b also closes to energize solenoid 131 to operate the air valve 132 and thereby cause the retraction of carrier 82 by operation of cylinder 86. After the shell in the carrier has been moved toward the mandrel, the photoelectric cell detects the absence of a shell opposite the cell 95 and the detector relay is deenergized, causing opening of contacts D2 for deenergizing solenoid 130 while solenoid 131 is operating.

At the end of the operational cycle of the trimming machine, a return of the slide 11 to its start position causes reclosing of contact LS- tb which causes energization of relays CR1, contact CR1-c of which closes to operate the feeder solenoid 130 again. Continuing automatic cycling of the trimming machine will be carried on until the supply of shells in the guideway 90:: is exhausted. When this occurs, the detector D is deenergized and the contacts D2 are reopened to prevent any further operation of the automatic feeder and therefore the trimming machine will not operate further until additional shells have been supplied into the guideway and carrier 82.

Attention is directed to the modified form of the invention shown diagrammatically in FIG. 8 wherein the mandrel 37x is connected to the pinion 26x, substantially in the manner shown in FIG. 2. A circular slicing knife 20x is mounted for rotation about an axis a and is connected with a pinion 22x which meshes with the pinion 26x so as to synchronize the rotation of knife 20:; with the rotation of mandrel 37x. It will be noted here that the gearing and sizes of the knife 20x and mandrel 37x is such as to cause the edge of the knife 20x at the point of convergence or overlap with the mandrel 37x to move at a substantially faster linear speed than the corresponding point on the mandrel, and the slicing action on the shell applied to the mandrel is obtained with this apparatus as well as with the apparatus shown in FIG. 1.

The method of developing the edge 41 for the knife so as to be properly shaped for continuous cutting with the mandrel of a particular configuration is described in connection with FIGS. 13 and 14. It is desirable that the accessory indicated in general by numeral be employed for developing the edge of the knife, but

it should be understood that the same method employed in the use of the accessory 140 may be employed by using the actual trimming machine. The accessory 144 has a frame structure 141 defining an elongate linear groove 142 in the top surface 143 thereof. At the left end of the groove is a stop 144 disposed closely adjacent the bottom of the groove. A slide 145 is constructed of a flat plate having a raised border portion 146 at the top and one end thereof and a plurality of clips 147 are secured on the slide 145 for holding a sheet of cardboard 148 or the like. The slide 145 has a rack 149 afiixed to the back side thereof and a rack 149 meshes with a pinion 150 which is journalled in the frame structure 14 1 beneath the slide and has a pitch diameter identical to the pitch diameter of pinion 26 in the trimming machine. The pinion 150 has a central hub 151 which extends upwardly through the enclosure 152 for the pinion 150 and the hub has a pair of pins :153 thereon. In the process of developing the contour of the knife edge, a cardboard template 154 with holes punched therein to receive the pins 153, is cut to the dimensions corresponding to the internal configuration of the shell to be trimmed and then a nominal inch is cut off the entire periphery of the template 154. This template is to simulate the mandrel of the trimming machine. The slide 145 is moved to the extreme right and the template 154 is applied to the hub '151 and the periphery of the template 154 is scribed on the cardboard 148. The slide is then moved a short distance to the left and the periphery of the template is again scribed on the cardboard 148. The slide is then successively moved in small increments to the left and at each increment the periphery of the template 154 is traced on the cardboard. When the slide reaches the extreme left hand position, a line will have been developed on the cardboard 148 which is identical to the configuration which is to be produced on the knife 24 It will be noted that the size of the pinion 150 is in excess of the size of the template 154 and therefore the provision is made in the producing of the knife edge configuration for the slicing effect which the knife 20 obtains on the trimming machine. Cardboard 148 is removed from the slide 145 and is glued to a piece of tool steel which is hand sawed approximately to the line. The steel is then heat treated and ground to the specified thickness. The knife is ready for application to the carriage 11 of the trimming machine and is ready to use. The method by which the knife edge is developed is extremely quick and may be completely accomplished in five to ten minutes.

It should be understood that this same method of developing the line on the cardboard 148 may be accomplished through the actual use of the slide 11 on the trimming machine and the use of a template simulating a mandrel. The actual mandrel used will be slightly larger than the template and therefore the knife edge and mandrel edge will overlap as described.

It will, of course, be understood that various changes may be made in the form, detail, arrangement and proportion of the parts Without departing from the scope of the invention which consists of the matter described herein and set forth in the appended claims.

What is claimed is:

1. Apparatus for trimming the peripheral edge of a drawn sheet metal shell or the like, comprising a shell mounting mandrel substantially identical in shape to the interior of the shell for receiving the shell thereover, said mandrel having a peripheral cutting edge over which the untrimmed shell extends, a knife at one side of the mandrel and having a slicing edge aligned with the mandrel cutting edge in overlapped cooperative cutting relation, drive means moving the knife along the mandrel, a positive drive interconnecting the mandrel and knife and moving the mandrel when the knife is moving, said drive producing convergent movement of said edges progressively one along the other and moving the point of convergence along the mandrel cutting edge at a first speed and said means also moving the point of convergence along the knife slicing edge at a second speed which is continuously greater than said first speed, whereby the shell periphery is continuously cut With a slicing action between the edges and is continuously urged inwardly toward the mandrel to facilitate the production of a smooth and clean edge.

2. Apparatus for trimming the peripheral edge of a drawn sheet metal shell or the like, comprising a shellmounting mandrel substantially identical in shape to the interior of the shell for receiving the shell thereover, said mandrel having a peripheral cutting edge over which the nut-rimmed shell extends, an elongate knife at One side of the mandrel and having a slicing edge aligned with the mandrel cutting edge in overlapped cooperative cutting relation therewith, drive means connected with the knife and longitudinally moving the knife along the mandrel, a positive drive connecting the mandrel to the knife and rotating the mandrel about an axis extending through the shell and transversely of the mandrel cutting edge as the knife is moved, said positive drive moving the mandrel edge in a direction similar to the direction of movement of the knife edge at the point of cutting, said positive drive causing the mandrel edge to move at the point of cutting along the knife edge at a speed substantially less than the speed of the knife edge, whereby to continuously urge the shell toward the mandrel and to cut the shell around the entire periphery thereof with a slicing action between the edges to materially reduce the power necessary to produce the cutting.

33. Apparatus for trimming the peripheral edge of a drawn sheet metal shell or the like, comprising a shellmounting mandrel substantially identical in shape to the interior of the shell for receiving the shell thereover, said mandrel having a peripheral cutting edge over which the untrimmed shell extends, an elongate knife at one side of the mandrel and having a slicing edge aligned with the mandrel cutting edge in overlapped cooperative cutting relation, a rotary mounting carrying the mandrel and rotating about an axis extending through the mandrel and transversely of the cutting edge thereof, said mounting having a coaxial pinion thereon with a pitch diameter in excess of twice the maximum radial distance from the rotation axis to the mandrel periphery, a linear rack meshed with the pinion and extending longitudinally of the knife and being afiixed thereto, means supporting said mounting for rotation and supporting said knife and rack for longitudinal reciprocation, means reciprocating the knife and rack whereby to turn the pinion, said knife edge being developed with respect to the mandrel to remain in overlapped cooperative cutting relation around the entire mandrel periphery and along the length of the knife, whereby to produce a speed differential between the knife edge and the mandrel edge wherein the knife edge speed is continuously in excess of the mandrel edge speed to thereby continuously urge the shell against the mandrel at the point of cutting and thereby prevent relative movement between the shell and mandrel and to cut the entire periphery of the shell with a slicing action between the edges of the mandrel and knife to produce a smooth and clean edge on the shell.

4. Apparatus for trimming and removing the peripheral edge of a drawn sheet metal shell, comprising a frame structure, a shell-mounting mandrel substantially identical in shape to the interior of the shell and having an outer end portion for receiving the shell thereover, said mandrel also having an inner end portion with a peripheral cutting edge over which the untrim-med shell extends, said mandrel also having a metal cutting anvil edge disposed inwardly from said cutting edge and adjacent thereto and being oriented transversely of the peripheral cutting edge for overlying the excess material of the shell to be trimmed therefrom, a rotary mounting on the frame and having an end portion secured to said mandrel and also having an elongate keyway in said end portion and extending toward and away from said anvil edge, a knife at one side of the mandrel and having a cutting edge aligned with the mandrel cutting edge in over-lapped cut ting relation, means movably mounting the knife on the frame structure and guiding the knife in movement to maintain the knife edge and mandrel edge in cooperative cutting relation, drive means moving the knife and rotating said mounting for producing cooperative cutting action of said cutting edges and thereby trimming the edge of the shell and producing a ring of scrap, and a reciprocable scrap knife slidably mounted on the frame structure for movement toward and away from the anvil and aligned with the mandrel edge in cutting relation therewith for splitting the ring of scrap, said scrap knife having an elongate keying insert interfitting with the keyway in the mounting to permit movement of the scrap knife into proximity with the anvil edge only when the mandrel and mounting are in predetermined position, and

16 means for reciprocating said scrap knife, whereby to produce trimming of the excess material at the peripheral edge of the sheet metal shell and splitting of the ring of scrap produced.

References Cited in the file of this patent UNITED STATES PATENTS 774,072 Hall Nov. 1, 1904 843,789 Beck Feb. 12, 1907 1,354,874 Beck Oct. 5, 1920 1,570,726 Broderick Jan. 26, 1926 1,934,660 Fairchild Nov. 7, 1933 2,154,028 Brosman et a1 Apr. 11, 1939 2,360,007 Muller Oct. 10, 1944 2,575,104 Halowich Nov. 13, 1951 2,577,316 Ern Dec. 4, 1951 2,636,402 Shaler Apr. 28, 1953 

1. APPARATUS FOR TRIMMING THE PERIPHERAL EDGE OF A DRAWN SHEET METAL SHELL OR THE LIKE, COMPRISING A SHELL MOUNTING MANDREL SUBSTANTIALLY IDENTICAL IN SHAPE TO THE INTERIOR OF THE SHELL FOR RECEIVING THE SHELL THEREOVER, SAID MANDREL HAVING A PERIPHERAL CUTTING EDGE OVER WHICH THE UNTRIMMED SHELL EXTENDS, A KNIFE AT ONE SIDE OF THE MANDREL AND HAVING A SLICING EDGE ALIGNED WITH THE MANDREL CUTTING EDGE IN OVERLAPPED COOPERATIVE CUTTING RELATION, DRIVE MEANS MOVING THE KNIFE ALONG THE MANDREL, A POSITIVE DRIVE INTERCONNECTING THE MANDREL AND KNIFE AND MOVING THE MANDREL WHEN THE KNIFE IS MOVING, SAID DRIVE PRODUCING CONVERGENT MOVEMENT OF SAID EDGES PROGRESSIVELY ONE ALONG THE OTHER AND MOVING THE POINT OF CONVERGENCE ALONG THE MANDREL CUTTING EDGE AT A FIRST SPEED AND SAID MEANS ALSO MOVING THE POINT OF CONVERGENCE ALONG THE KNIFE SLICING EDGE AT A SECOND SPEED WHICH IS CONTINUOUSLY GREATER THAN SAID FIRST SPEED, WHEREBY THE SHELL PERIPHERY IS CONTINUOUSLY CUT WITH A SLICING ACTION BETWEEN THE EDGES AND IS CONTINUOUSLY URGED INWARDLY TOWARD THE MANDREL TO FACILITATE THE PRODUCTION OF A SMOOTH AND CLEAN EDGE. 